Air springs have been used for motor vehicles and various other machines and equipment for a number of years. The springs provide cushioning between movable parts, primarily to absorb shock loads imparted thereon. The air spring consists of at least one flexible elastomeric reinforced sleeve extending between a pair of retainers, forming a pressurized chamber therein. The sleeve typically has a relatively inextensible bead core at each end for securing the sleeve to the retainers. Alternatively, the sleeve may be secured to the retainers by conventional crimping means. There may be one or more pistons associated with the air spring. The retainers also assist in securing the air spring on spaced components or parts of the vehicle or equipment by being secured to a mounting plate which is attached to the moveable part of the vehicle or machine.
The fluid in the pressurized chamber, generally air, absorbs most of the shock impressed upon or experienced by one of retainers. The retainers move towards and away from each other when the air spring is subjected to any forces.
Both upper and lower retainers are conventionally formed of stamped metal. If the air spring has a piston, the piston, upon which the lower retainer is secured, may be metal or thermoplastic. A bumper, mounted on either retainer and provided for impact absorption and transference, is usually thermoplastic or thermoelastic, depending upon the forces which will ultimately be acting on the air spring and the forces to which the bumper will be subjected.
When the air spring is mounted to a vehicle, a subassembly made from coated steel stampings and plumbing components are used to achieve the mounting attachment, air connection and airsleeve bead captivation. Such conventional mounting means are illustrated in the following U.S. Pat. Nos. 5,203,585; 5,464,245; 5,403,031, 5,346,247, and 4,733,876 (which has a two material upper retainer which has a mounting structure rising from two cojoined flat plates). Other known air springs and retainers are disclosed by U.S. Pat. No. 5,535,994 and EP 295,392.